Wheelbuilding / Wheel Building / Wheel build help

Slick up to the 46c Specialized (>30psi) runs excellent on standard rims (RS11&thelikes) - the Kojak 35c slick fails on steep velodrome banking at 30psi on R500&thelikes rim.

You can CX with 33c knobbies on standard rims, but you need to inflate them more than you enjoy to keep them from squirming in the grippy cornering on grass. Wider than standard rims would help you here.

You could go up to a 28mm external width rim with 28mm tyres. Assuming you're looking at 28C road tyres and 38C knobblies (not really CX, as they are too wide for UCI racing), you should be alright with 28mm rims. Going too wide on the rims with knobblies can be troublesome because the tread design will probably have been designed for a more rounded tyre profile. Past about ⅔ of nominal tyre width, you're getting experimental

If you want to use 28-38 mm tyres, I'd say you want a touring rim, something in the Mavic range, something like 719. If you are on discs there is even more choice of lighter rims

Thanks guys, I'll be running discs so will have a look around at various options.

Isn't the tendency these days to have very narrow rims? Is everybody doing it wrong?

I don't know what discipline you're talking about but we're definitely seeing wider road rims.